Quadrasteer? That's GM speak for four-wheel steering. 4WS was introduced to last year's truck line-up and concurrently won the Automobile Journalists Association of Canada's (AJAC) annual award for "Best New Technology". Basically the system increases high-speed stability while allowing for much easier low-speed maneuverability - especially while parking. It's uncanny really. I found myself purposely pulling into supermarket parking lots - something I don't usually enjoy - and zipping into tight parking spaces just for fun. OK, obviously it was a slow week for entertainment. Quadrasteer gives the large truck the manageability of a much smaller vehicle, reducing the turning circle by 21% to 11.4 m (37.4 ft). Out on the highway it not only feels safer in all weather conditions but gives the big truck sportier handling characteristics.
How does it work? It uses the Sierra's conventional front-wheel hydraulic power steering in tandem with an electrical rear-wheel steering system, changing the angle of the rear wheels. For lower speeds it turns them opposite to the front wheels while for highway speeds the wheels turn in the same direction.
Though I didn't test its trailer towing capability specifically, it's easy to surmise that it should improve. To paraphrase, GM states that highway speed lane changes are quicker and safer with virtually no trailer 'fishtailing'. It also benefits city driving, allowing less need to overcompensate for the turn by pulling wide into the adjacent lane.
With towing in mind, GM's Hydra-Matic 4-speed automatic uses a tow/haul mode selector to delay up-shifts, reducing the transmissions normal desire to search up and down for the optimal gear while on uphill grades. Anyone who has towed a trailer knows that the 'grunt' of a large-displacement V8 is paramount for scaling a steep hill at a respectable speed. To that end the Denali's 325-hp 6.0-L OHV V8 puts out an ample 370 lb-ft of torque. The low-emission, LEV rated engine puts power down to the road through a permanent all-wheel drive system.